Tissue Engineering Auricular Cartilage: A Review of Auricular Cartilage Characteristics and Current Techniques for Auricular Reconstruction.

Microtia and anotia are congenital auricular anomalies that negatively impact the psychosocial development of those affected. Because auricular cartilage is a type of elastic cartilage that lacks regenerative capacity, any notable defect in its structure requires a surgical approach to reconstructing the auricle. While there are several reconstructive options available between alloplastic and prosthetic implants, autologous rib cartilage grafts remain the most commonly used treatment modality. Still, this widely used technique is accompanied by significant patient discomfort in a young child and carries additional risks secondary to the traumatic process of rib cartilage extraction, such as pneumothorax and chest wall deformities, and the final esthetic results may not be ideal. To circumvent these limitations, tissue engineering approaches have been used to create a realistic-looking ear that mirrors the complex anatomy of the normal ear. This article reviews the biochemical and biomechanical properties of human auricular cartilage as they relate to design criteria. In addition, a variety of cell sources, biocompatible scaffolds, scaffold-free techniques, and mechanical and biological stimuli are discussed. This review aims to identify knowledge gaps in the literature related to auricular cartilage characteristics and make recommendations to drive the field of auricular tissue engineering.

Diagnostic Arthroscopy of the Minipig Stifle (Knee) for Translational Large Animal Research.

To gain regulatory approval for the clinical use of knee biologics and devices in humans, translational large-animal studies are typically required. Animal models that permit second-look arthroscopy are valuable because they allow for longitudinal assessment of the treated tissue without needing to sacrifice the animal. The minipig is an ideal preclinical animal model for the investigation of therapies for the knee, in part because arthroscopy can be performed in its stifle (knee) joint with the use of standard surgical equipment used in humans. The purpose of this Technical Note is to describe a reproducible technique for diagnostic arthroscopy of the minipig stifle (knee) joint.

Adult Dermal Stem Cells for Scaffold-Free Cartilage Tissue Engineering: Exploration of Strategies.

Dermis-isolated adult stem (DIAS) cells, abundantly available, are attractive for regenerative medicine. Strategies have been devised to isolate and to chondroinduce DIAS cells from various animals. This study aimed to characterize DIAS cells from human abdominal skin (human dermis-isolated adult stem [hDIAS] cells) and to compare and to refine various chondroinduction regimens to form functional neocartilage constructs. The stemness of hDIAS cells was verified (Phase I), three chondroinduction pretreatments were compared (Phase II), and, from these, one regimen was carried forward for refinement in Phase III for improving the mechanical properties of hDIAS cell-derived constructs. Multilineage differentiation and mesenchymal stem cell markers were observed. Among various chondroinduction pretreatments, the nodule formation pretreatment yielded constructs at least 72% larger in diameter, with higher glycosaminoglycan (GAG) content by 44%, compared with other pretreatments. Furthermore, it was found that culturing cells on nontissue culture-treated surfaces yielded constructs (1) on par with constructs derived from aggrecan-coated surfaces and (2) with superior mechanical properties than constructs derived from cells cultured on tissue culture-treated surfaces. After the nodule formation pretreatment, combined supplementation of TGF-ß1, IGF-I, and fetal bovine serum significantly enhanced aggregate modulus and shear modulus by 75% and 69%, respectively, over the supplementation by TGF-ß1 alone. In summary, human skin-derived DIAS cells are responsive to chondroinduction for forming neocartilage. Furthermore, the mechanical properties of the resultant human constructs can be improved by treatments shown to be efficacious in animal models. Advances made toward tissue-engineering cartilage using animal cells were shown to be applicable to hDIAS cells for cartilage repair and regeneration.

Validation of MRI and Surgical Decision Making to Predict a Complete Resection in Pelvic Exenteration for Recurrent Rectal Cancer.

BACKGROUND: The main predictor of long-term survival in patients with recurrent rectal cancer is surgical resection with a clear resection margin. MRI plays a role in patient selection and surgical planning. OBJECTIVE: This study aimed to validate MRI in determining pelvic involvement by comparing MRI to histological outcomes, to assess the effect of MRI on surgical planning by comparing MRI findings with the surgical procedure, and to compare MRI anatomical involvement with resection outcome to assess if MRI can predict a clear resection margin. DESIGN: Retrospective study reviewing prepelvic exenteration MRI and correlating organ, involving an MRI with pathological involvement and surgical outcomes. SETTINGS: Single quaternary referral center with a special interest in pelvic exenteration. PATIENTS: The patients included 40 men and 22 women with median age of 60 years who had locally recurrent rectal cancer. MAIN OUTCOME MEASURES: The accuracy of MRI as measured using sensitivity and specificity by correlating MRI involvement with pathological involvement was the primary outcome measured. RESULTS: Recurrence in the anterior and central compartments was identified with accuracy on MRI and was likely to be associated with clear resection margins. MRI was less accurate at determining pelvic sidewall involvement. Lateral recurrence, high sacral, and nerve involvement were more likely to be associated with a positive resection margin. Sensitivity and specificity for pelvic sidewall structures was 46% and 91%. Involvement of nerve roots (60%-69%) and the upper sacrum (80%) on MRI was more likely to predict a positive resection margin than involvement of major pelvic viscera (22%). LIMITATIONS: This study was limited by its retrospective nature. CONCLUSIONS: MRI findings can be used to help predict resection margin. Prospective work with MRI interpretation and close correlation and involvement by pathologists is needed to address imaging and surgical limitations at the pelvic sidewall and high posterior margin.

Clinical, MRI, and PET-CT criteria used by surgeons to determine suitability for pelvic exenteration surgery for recurrent rectal cancers: a Delphi study.

BACKGROUND: Surgical resection with clear margins is the major predictor of long-term survival in recurrent rectal cancer. The extent of pelvic exenteration surgery depends on many factors including clinical and radiological criteria. OBJECTIVE: The aim of this study was to establish which clinical, MRI, and PET criteria were considered important by surgeons who perform pelvic exenteration surgery, when assessing a patient with recurrent rectal cancer for pelvic exenteration surgery. DESIGN: A 2-stage Delphi study was conducted among an international panel of 36 colorectal surgeons recruited via a snowball-sampling method. Surgeons rated the importance of 99 clinical and radiological criteria by using a 9-point scale. MAIN OUTCOME MEASURES: Consensus was attained when at least 85% of the panel rated criteria within 3 points. RESULTS: Clinical factors suggestive of systemic disease, symptoms of advanced local recurrence such as pain, surgical fitness, and cognitive impairment were considered important by the panel when considering suitability for surgery. Agreement regarding the indication for surgery was reached for 20 radiological factors. Strong agreement was achieved for factors associated with tumor involvement in the axial and anterior compartments. For only 16 of these 20 radiological factors was there an agreement that a clear resection margin was likely to be achieved. LIMITATIONS: Further rounds of Delphi may have yielded greater consensus. CONCLUSION: This study has identified a set of criteria considered by experts to be important in evaluating patients' suitability for pelvic exenteration surgery. Evaluation of these criteria is required to determine their clinical utility in predicting a negative resection margin at pelvic exenteration surgery.

Magnetic resonance imaging appearance of cartilage repair in the knee.

Assessment of surgically repaired cartilage lesions with standardized cartilage sensitive magnetic resonance imaging was done to evaluate the integrity, morphologic features, and signal of the articular surface, thereby obtaining information about the natural history of these procedures in the knee. Magnetic resonance imaging also assessed the interface between the repaired and native cartilage, changes in the subchondral bone, and the appearance of cartilage over the opposite and adjacent (native) surfaces. One hundred eighty magnetic resonance imaging examinations were obtained in 112 patients who had cartilage-resurfacing procedures, including 86 microfractures and 35 autologous chondrocyte implantations, at a mean of 15 and 13 months after surgery, respectively. Autologous chondrocyte implantations showed consistently better fill of the defects at all times compared with microfracture. The graft hypertrophied in 63% of surgeries. The repair cartilage over the microfracture generally was depressed with respect to native cartilage. Propensity for bony overgrowth was most marked in the microfracture group, with loss of adjacent cartilage evident with progressive followup.